radiobiologyfandomcom-20200213-history
How Cancer Forms
'How does a cell become cancer?' There are hundreds of different types of cancer, but overall, cancer is characterized by out-of-control cell growth. Cells in your body contain chromosomes formed from super-condensed deoxyribonucleic acid, or DNA. DNA is a twisted double helix of two polynucleotide strands that contain long strings of information. Genes are long sequences along the DNA strand which are coded messages that give the cell a specific instruction on how to create something or how to behave. For example, this could be the instructions to synthesize a protein, or the creation of other molecules such as ribonucleic acid (RNA). Genes dictate the behaviour of the cell, and thus control the cell type, cell behaviour and function, when it will divide, and when it will die. As humans grow and ago, new cells will form. The DNA replicates itself, copying its exact sequence in a semi-conservative way. However, sometimes this process can go wrong. Sometimes a mistake is made when replicating the DNA, so the sequence of the DNA molecules is altered, and thus the gene is different. Although DNA has repair mechanisms, errors that are not fixed become permanent mutations. Although changes in genes can happen by chance when a cell divides, mutations can also occur due to processes inside the cell or from external factors such as chemicals or tobacco. Alternatively, you can inherit particular genes that make it more likely for that cell to develop cancer. Regardless of the cause, Cancer can form when these mutations become harmful. The specific mutation will determine the effect on the cell. Some mutations cause the cell to no longer follow its instructions for behaving and function and start to grow out of control. Other mutations may cause a cell to produce excessive proteins that trigger a cell to undergo division, or stops the production of a protein that would normally tell a cell to stop dividing. When these altered cells divide uncontrollably, they form masses of tissues called tumors. The growth of the tumor, its interference with the systems of the body such as digestive, nervous, and circulatory, and their ability to release hormones that can alter bodily functions, can be harmful. Comparatively, tumors may be classified as benign if they stay in one place and demonstrate a limited growth, and thus are relatively harmless 6. Benign versus Malignant Growth A tumor forms when abnormal cells divide uncontrollably and forms a lump. However, there are two types of tumors, benign (non-cancerous) and malignant (cancerous). Although benign tumors have the potential to become dangerous or malignant, they are usually not life-threatening and do not cause much damage. Conversely, malignant tumors can spread into the surrounding tissues, destroy the surrounding tissues, and cause other tumors to develop. Thus, they can be life-threatening. For the tumor to keep growing, they create their own blood vessel systems in order to supply them with their necessary oxygen, glucose, or any other hormones for their continual and increased growth. This process of developing a blood supply system is termed angiogenesis 3. This diagram shows the progression of a tumor forming from normal cells and the process of angiogenesis taking place as a blood supply system for the tumor is established. Source: Cancer Council Victoria 1 After this process of angiogenesis is complete, invasion of the tumor into surrounding tissue can take place, and the cancer becomes classified as invasive. Invasive cancers are increasingly dangerous as they can enter the bloodstream or lymphatic system and travel to various other parts of the body, forming tumors in another location. This diagram depicts an invasive tumor, with its cancer cells traveling to other regions of the body through blood vessels or lymph channels, in order to initiate the formation of new tumors in other locations of the body. Source: Patient Info 4 References 1 “Advanced Cancer.” Life during and after Childhood Cancer - Cancer Council Victoria, www.cancervic.org.au/cancer-information/advanced-cancer. 2 “Genetics 101.” ThinnerGene DNA Diet and Exercise Program, www.thinnergene.com/about-thinnergene/genetics-101/. 3 “How Do Cancer Cells Grow and Spread?” Current Neurology and Neuroscience Reports., U.S. National Library of Medicine, 21 Sept. 2016, www.ncbi.nlm.nih.gov/books/NBK279410/. 4 “How Do Cancers Grow and Spread? | Stages of Cancer.” Patient.info, Patient.info, patient.info/health/cancer/stages-of-cancer. 5 Team, The MNT Editorial. “Cancer: What You Need to Know.” Medical News Today, MediLexiconInternational, 30 Mar. 2016, www.medicalnewstoday.com/info/cancer-oncology. (Date Accessed Oct. 2018) 6 “What Is Cancer? - Cancer Treatment Centers of America |CTCA.” CancerCenter.com, 1 Jan. 1AD,www.cancercenter.com/what-is-cancer/. (Date Accessed Oct. 2018)